Agricultural Entomology: Pests and Diseases of Paddy Management

Dr.C.MABEL JOSHALINE Assistant Professor Dept.of Rural Development Science Arul Anandar College Madurai-625514 AGRICULTURAL ENTOMOLOGY

Pests & Diseases of Paddy Unit I-a Name, Symptoms, Diagram, Life cycle & IPM

1. Rice stem borer / Yellow stem borer Distribution: The yellow stem borer of rice attacks only rice and has wide distribution in all Asian countries. Symptoms : Larva feeds inside the stem causing drying of the central shoot called dead heart in young plant or drying of the panicle called white ear . October-December has been found conducive for the multiplication of the insect.

Life cycle The female lays 15 - 18 eggs in a mass near the tip on the upper surface of leaf and covers them with buff coloured hairs and scales. A female lays about 2 - 3 egg masses . Egg period ranges from 5 - 8 days. The newly hatched white larva enters the leaf sheath and feeds for 2 3 days and bores into the stem . Usually only 1 larva is found inside a stem Sometimes 2 - 4 larvae may also be noticed. The larva becomes full grown in 33 - 41 days . Its color is white or yellowish white

Before pupation it covers the exit hole with thin webbing and then forms a white case/ cocoon in which it pupates. The pupa is dark brown. The pupal period 6 -10 days Pupa breaks open to form adult The entire life-cycle is completed in 50 - 70 days.

IPM Removal and destruction of rice stubbles from field and also collection and destruction of egg masses. Clipping the tip of the seedlings prior to transplantation to eliminate egg masses. Collection and destruction of moths using light traps. Spraying of endosulfan 5% SC at 1 litre/ha of 10% dead heart is crossed in the nursery a week prior to pulling out the seedlings and the second after 15 days of transplantation. An economic threshold level of 10% dead heart in vegetative stage and presence of 1 moth or 1 egg mass/sq.m. in the ear-head bearing stage has been suggested for adoption of chemical method of control by giving a third spray with one of the above chemical pesticides. Seedlings root dip treatment for 12 or 14 hours before transplanting in 0.02% chlorpyriphos

2. Brown plant hopper- BPH Distribution: Distributed in Asia where rice is grown. It is known only to feed on rice Symptoms It attacks all stages Both nymphs and adult are present at the base of the tillers, plants and suck the sap and turn yellow and finally dry . Round yellow patches turn brown and dry up. This is called hopperburn . Life cycle The female lays eggs in two rows on either side of leaf . The average member of eggs laid varies from 250 - 350. The egg period is 6 -9 days Egg hatch out to nymph. Nymph period is 10 18 days. Nymphs grow to adults. The total life-cycle occupies 16 27 days. Control: Spraying carbaryl / moncrotophos1 litre/ha in the early stages of the crop. Application should be restricted to early stage of the crop.

3. Rice leaf folder Distribution: Occurs in all rice growing areas of our country. It is active from October to January. Symptoms The larva rolls the leaf blade by rolling its edges and sometimes even fold the leaf tip to the basal part of the leaf blade and feeds from inside by scraping. In Field the whole crop gives a sick appearance with white patches. The infestation at boot leaf stage of the crop results in heavy loss of grain yield Life cycle The brownish orange coloured moth . The eggs are laid singly or in pairs on the under of leaf . The egg period is 4 - 7 days. The pale yellowish green larva becomes full grown in 15 - 27 days and pupates inside the leaf roll. Pupal period is 6 - 8 days. Pupa breaks to give brown colour moth. Total life-cycle varies from 25 - 42 days. Control Removal of grass from field bunds. Spraying of monocrotophos at 1 litre/ha.

Diseases of paddy 1. Blast It is caused by fungus Symptoms Spots on all parts of shoot white to green or gray diamond-shapedspots with dark green borders death of leaf blades black necrotic patches on stem rotting panicles

Control Grow resistant variety Use clean, fungicide-treated seed. Plant early (April) to avoid the heavy rain Use the recommended N fertilizer rate. Avoid high N application Maintain a consistent, deep flood ( 4 inches) after the drain. Scout fields for leaf blast symptoms, especially on susceptible varieties. If leaf blast is present, a preventative fungicide application should be considered. Top dressing of potash 45kg/ha

Symptoms Panicle blast : Light brown dots early lesion gradually around panicle and rachis and the vertical extension of the diseased parts due to different varieties yellowish white, brown or black. Grain blast

White ears due to stem borer are chaffy, remains erect and can be easily pulled out whereas neck blast infected panicles bear blackish spot at the base, can not be pulled out easily and bear shriveled grains. Node blast Neck blast may be confused with white heads caused by stemborer. Both injuries showed empty, erect white gray panicle. Unlike injury caused by stemborer, where the entire stem can be pulled readily, neck blast causes only injury at the neck and does not extend further into the leaf sheath.

2. Brown spot It is caused by fungus Symptoms Circular, brown lesions on seedling and distorted leaves black discoloration of roots death of seedlings circular or oval lesions with gray center and reddish-brown margin on older plants brown or black spots on grain reduced number of grains Control Grow resistant Use clean, fungicide-treated seed. Plant early (April) to avoid the heavy rain Use the recommended N fertilizer rate. Avoid high N application

Brown Spot Brown Spot

IPM 1. Keep field clean 2. Grow resistant varieties 3. Avoid excess application of fertilisers & N application by Leaf Colour Chart (LCC) 4. Avoid heavy rain during maturity 5. Do seed treatment with biopesticide, biofertiliser, and pesticide 6. Raise trap crop like castor on bunds 7. Fix light traps in fields- 12/hac 8. Fix pheremone traps- 12/hac 9. Collect and burn the diseased plants 10. Apply neem seed kernel extract 5% / neem cake coated urea (5 : 1) 11. Apply 12.5t/hac of farm yard manure, green manure 12. Apply Pseudomonas fluroescens as seed treatment, soil application Pseudomonas fluorescens Seed treatment (10 g/kg), seedling dip (2.5 kg/ha), field application (2.5 kg/ha) 13. Apply Bacillus thuriengensis to control larvae 14. Avoid excessive irrigation & follow alternate wetting & drying 15. Follow crop rotation 16. Set up bird (owl) perches at 40 to 50 /ha